Fan unit having blades manufactured by blow molding and made from thermoplastic elastomer

ABSTRACT

A fan unit includes a fan casing and a plurality of blades extending radially and outwardly from the fan casing. Each of the blades includes a hollow blade body that is made from a thermoplastic elastomer, that is manufactured by a blow molding process, and that is exposed outwardly from the fan casing, and a coupler element that is fixed to the blade body and that is clamped between front and rear casing halves of the fan casing.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a fan unit, more particularly to a fan unit having blade bodies that are manufactured by a blow molding process and that are made from a thermoplastic elastomer.

[0003] 2. Description of the Related Art

[0004] Referring to FIG. 1, a conventional fan unit is shown to include a fan casing 1 and a plurality of blades 2 extending radially and outwardly from the fan casing 1.

[0005] The aforesaid conventional fan unit is disadvantageous in that the blades 2 are made from stiff plastics or metal so that a protective frame or a ventilation frame must be mounted to surround the fan unit in order to prevent injury to a person who accidentally touches the blades 2.

SUMMARY OF THE INVENTION

[0006] The object of this invention is to provide a fan unit having blade bodies that are manufactured by a blow molding process and and that are made from a thermoplastic elastomer so as to minimize injury to a person in case he or she accidentally touches the blades during operation of the fan unit.

[0007] Accordingly, a fan unit of the present invention includes a motor having an output shaft, a fan casing, a plurality of blades, and a fastener unit. The fan casing is mounted non-rotatably on the output shaft of the motor, and includes an annular rear casing half having a plurality of angularly spaced-apart groove units, and an annular front casing half disposed in front of the rear casing half and having a plurality of angularly spaced-apart groove units. The blades are mounted on and extend radially and outwardly from the front and rear casing halves. Each of the blades includes a hollow blade body that is made from a thermoplastic elastomer, that is manufactured by a blow molding process, and that is exposed outwardly from the front and rear casing halves, and a coupler element that is fixed to the blade body, that is clamped between the front and rear casing halves and that has a rearwardly-extending tongue unit received snugly in a respective one of the groove units in the rear casing half, and a frontwardly-extending tongue unit received snugly in a respective one of the groove units in the front casing half. The fastener unit fastens the front and rear casing halves securely so as to prevent removal of the blades from the front and rear casing halves.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other features and advantages of this invention will become apparent in the following detailed description of a preferred embodiment of this invention, with reference to the accompanying drawings, of which:

[0009]FIG. 1 is a perspective view of a conventional

[0010]FIG. 2 is an exploded view of a preferred embodiment of a fan unit according to the present invention;

[0011]FIG. 3 is a perspective view of the preferred embodiment;

[0012]FIG. 4 is a partly sectional view of the preferred embodiment; and

[0013]FIG. 5 is a sectional view of a blade taken along lines V-V of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Referring to FIGS. 2, 3 and 4, the preferred embodiment of a fan unit according to the present invention is shown to include a motor 100, a fan casing 10, a plurality of blades 20, and a fastener unit 50.

[0015] As illustrated, the fan casing 10 is mounted non-rotatably on an output shaft 110 of the motor 100, and includes an annular rear casing half 30 and an annular front casing half 40. The rear casing half 30 has a plurality of angularly spaced-apart groove units 34 that are defined by a plurality of groove-defining wall portions 332. The front casing half 40 is disposed in front of the rear casing half 30, and has a plurality of angularly spaced-apart groove units 44 that are defined by a plurality of groove-defining wall portions 432.

[0016] The blades 20 are mounted on and extend radially and outwardly from the front and rear casing halves 40, 30. Each of the blades 20 includes a hollow blade body 21 (see FIG. 5) that is made from a thermoplastic elastomer, that has a cross-section shaped as a teardrop, that is manufactured by a blow molding process, and that is exposed outwardly from the front and rear casing halves 40, 30, and a coupler element 22 that is fixed to the blade body 21, that is clamped between the front and rear casing halves 40, 30, and that has a rearwardly-extending tongue unit 223 which is received snugly in a respective one of the groove units 34 in the rear casing half 30, and a frontwardly-extending tongue unit 222 which is 44 in the front casing half 40.

[0017] The fastener unit 50 fastens the front and rear casing halves 40, 30 securely so as to prevent removal of the blades 20 from the front and rear casing halves 40, 30.

[0018] In this embodiment, the rear casing half 30 includes an annular outer wall 32 with a front end, an annular inner wall 31 that is disposed coaxially in the outer wall 32 to define a shaft hole 351 which permits extension of the output shaft 110 of the motor 100 therethrough and that has a front end flush with the front end of the outer wall 32, and a plurality of angularly spaced-apart rods 33 that extend radially and outwardly from the front end of the inner wall 31 to the front end of the outer wall 32 to form a plurality of parallel grooves 331 which constitute a respective one of the groove units 34 in the rear casing half 30. The front casing half 40 includes an outer wall 42 that is aligned with the outer wall 32 of the rear casing half 30 and that has a rear end, an inner wall 41 that is disposed coaxially in the outer wall 42, and that has a rear end flush with the rear end of the outer wall 42, and a plurality of angularly spaced-apart rods 43 that extend radially and outwardly from the rear end of the inner wall 41 of the front casing half 40 to the rear end of the outer wall 42 of the front casing half 40 to form a plurality of parallel grooves 431 which constitute a respective one of the groove units 44 in the front casing half 40.

[0019] The rear casing half 30 further includes a coupling tube 35 that extends coaxially and frontwardly from the front end of the inner wall 31 of the rear casing half 30 through the inner wall 41 of the front casing half 40, and that has an external thread portion 353 and an inner wall surface formed with a planar portion 352 engaging a planar portion 130 of an outer wall surface of the output shaft 110 to prevent relative rotation therebetween. The fastener unit 50 is threadedly mounted on the external thread portion 353 of the coupling tube 35 so as to press the front casing half 40 against the rear casing half 30, thereby preventing relative rotation between the front and rear casing halves 40, 30. The fastener unit 50 includes an internally threaded sleeve 51 and a plurality of actuator elements 53 extending radially and outwardly from the sleeve 51 to facilitate turning of the sleeve 51 on the coupling tube 35. A locking knob 120 is mounted threadedly on an outer end of the output shaft 110 of the motor 100 to prevent undesired removal of the sleeve 51 from the motor 100.

[0020] Note that the coupler element 22 of each of the blades 20 has a tongue-mounting strip 224 which extends in a radial direction of the fan casing 10 and which is formed with two opposite side faces. Each of the rearwardly and frontwardly extending tongue units 223, 222 includes a plurality of tongues 223″, 222″ that are formed integrally with a corresponding one of the opposite side faces of the tongue-mounting strips 224. The tongues 223″ of the rearwardly-extending tongue units 223 are aligned respectively with the tongues 222″ of the frontwardly-extending tongue units 222. Preferably, the tongues 223″, 222″ are constructed as ribs.

[0021] Since the blade bodies 21 are hollow, and are made from a thermoplastic elastomer, in case a person accidentally touches the same during rotation of the fan unit, only minor injury will be caused to the person. The object of the present invent is thus achieved.

[0022] With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated by the appended claims. 

I claim:
 1. A fan unit comprising: a motor having an output shaft; a fan casing mounted non-rotatably on said output shaft of said motor and including an annular rear casing half having a plurality of angularly spaced-apart groove units, and an annular front casing half disposed in front of said rear casing half and having a plurality of angularly spaced-apart groove units; a plurality of blades mounted on and extending radially and outwardly from said front and rear casing halves, each of said blades including a hollow blade body that is made from a thermoplastic elastomer, that is manufactured by a blow molding process and that is exposed outwardly from said front and rear casing halves, and a coupler element that is fixed to said blade body, that is clamped between said front and rear casing halves and that has a rearwardly-extending tongue unit received snugly in a respective one of said groove units in said rear casing half, and a frontwardly-extending tongue unit received snugly in a respective one of said groove units in said front casing half; and a fastener unit for fastening said front and r ear casing halves securely so as to prevent removal of said blades from said front and rear casing halves.
 2. The fan unit as defining in claim 1, wherein said rear casing half includes an annular outer wall with a front end, an annular inner wall that is disposed coaxially in said outer wall to define a shaft hole which permits extension of said output shaft of said motor therethrough and that has a front end flush with said front end of said outer wall, and a plurality of angularly spaced-apart rods that extend radially and outwardly from said front end of said inner wall to said front end of said outer wall to form a plurality of parallel grooves which constitute a respective one of said groove units in said rear casing half, and wherein said front casing half includes an outer wall that is aligned with said outer wall of said rear casing half and that has a rear end, an inner wall that is disposed coaxially in said outer wall, and that has a rear end flush with said rear end of said outer wall of said front casing half, and a plurality of angularly spaced-apart rods that extend radially and outwardly from said rear end of said inner wall of said front casing half to said rear end of said outer wall of said front casing half to form a plurality of parallel grooves which constitute a respective one of said groove units in said front casing half.
 3. The fan unit as defined in claim 2, wherein said output shaft of said motor has an annular outer wall surface that is formed with a planar portion, said rear casing half further including a coupling tube that extends coaxially and frontwardly from said front end of said inner wall of said rear casing half through said inner wall of said front casing half, and that has an external thread portion and an inner wall surface formed with a planar portion which engages said planar portion of said outer wall surface of said output shaft to prevent relative rotation therebetween, said fastener unit being threadedly mounted on said external thread portion of said coupling tube so as to press said front casing half against said rear casing half, thereby preventing relative rotation between said front and rear casing halves.
 4. The fan unit as defined in claim 3, wherein said coupler element of each of said blades has a tongue-mounting strip which extends in a radial direction of said fan casing and which is formed with two opposite side faces, each of said rearwardly and frontwardly extending tongue units including a plurality of tongues that are formed integrally with a corresponding one of said opposite side faces of said tongue-mounting strips, said tongues of said rearwardly-extending tongue units being aligned respectively with said tongues of said frontwardly-extending tongue units.
 5. The fan unit as defined in claim 4, wherein said tongues are constructed as ribs.
 6. The fan unit as defined in claim 1, wherein each of said blade bodies has a cross-section that is shaped as a teardrop. 